What's the problem with a 5 minute cooldown? You should know which server you want to join, and by the time you're finished with that server the 5 minutes will be up. Also, if the cooldown is initiated in the first place, it means you've already kicked someone anyway, which has already inconvenienced them - surely you don't want to inconvenience another person in such a short space of time?
Whilst donating DOES provide perks to donators, such as server priority, it should not impede on other peoples' enjoyment of MCSG, which it has been doing with the low cooldown time (hence lots of people getting kicked). I would expect this is why the time has been increased to 5 minutes.